First off the answer is NO, you are not "screwed"... You are going to learn more about sewing machines than you thought, but that is about it.
A good first step would be a couple of photos posted so we can see what's up. Focus on the underside and any thing that looks to be connected to the stitch length adjuster.
I ALWAYS take pictures of each part of a machine before i take it apart.
I also try to mark (or make good observations) of how parts orient and take notes.
Remember, they put it together, so can you.